Use of non-ionic surfactants to increase oxygen scavenger activity of functionalized polyolefin films

ABSTRACT

An oxygen-scavenging composition comprising (I) an oxidizable metal component, (II) an electrolyte component, (III) a non-electrolytic, acidifying component, and (IV) a non ionic surfactant component, preferably selected from the group consisting of alkyl polyethylene glycol ethers, polyethylene glycols, polypropylene glycols, polypropylene glycol polyethylene glycol block copolymers and polyethylene polyethylene glycol block copolymers.

There are many products which have to be kept in a closed volume orpackaged with little or almost no oxygen. These oxygen-sensitiveproducts include pharmaceuticals, food products, meats, beverages, etcwhich are susceptible for degradation due to the presence of oxygen

Limiting the exposure to oxygen provides a means to maintain and enhancethe quality and shelf-life of the packaged product. The removal ofoxygen from the packaged foods and building barriers against oxygenpenetration during storage represents an important objective for thefood packaging technologist. For example packaging a food product in apackage capable of minimizing oxygen exposure is a means to maintain thequality of the packaged product over an extended time and to retardspoilage of the product so that it is maintained in invent-tory longerwithout wastage and the need of restocking and replacement.

In the food packaging industry, several techniques have been developedto limit oxygen sensitive packaged materials to oxygen exposure. Suchtechniques include the use of barrier material (with low permeability tooxygen) as part of the packaging; the inclusion of some means capable ofconsuming oxygen other then the packaging material (through the use ofsachets with material capable of reacting with oxygen); and the creationof a reduced oxygen environment within the package (e.g. modifiedatmosphere packaging-MAP- and vacuum packaging).

Even if each of the above techniques has its place in the industry, itis well recognized that the inclusion of an oxygen scavenger as a partof the packaging article is one of the most desirable means of limitingoxygen exposure.

Product sensitive to oxygen, particularly foods, beverages andmedicines, deteriorate or spoil in the presence of oxygen. One approachto reducing these difficulties is to package such products withpackaging materials containing at least one layer of a so-called“passive” gas barrier film that can act as a physical barrier totransmission of oxygen but does not react with oxygen. Films of ethylenevinyl alcohol copolymer (EVOH) or polyvinylidene dichloride (PVDC) arecommonly used for this purpose due to their excellent oxygen barrierproperties. By physically blocking transmission of oxygen, these barrierfilms can maintain or substantially maintain initial oxygen levelswithin a package. Because passive barrier films can add cost to apackaging construction and do not reduce levels of oxygen alreadypresent in the packaging construction, however, there is a need foreffective, lower cost alternatives and improvements.

An approach to achieving or maintaining a low oxygen environment insidea package is to use a packet containing an oxygen absorbent material.The packet, also sometimes referred to as a pouch or sachet, is placedin the interior of the package along with the product. Sakamoto et al.discloses oxygen absorbent packets in Japan Laid Open Patent ApplicationNo. 121634/81 (1981). A typical ingredient used in the oxygen scavengercarried in the packet is reduced iron powder which can react with oxygento form ferrous oxide or ferric oxide, as disclosed in the U.S. Pat. No.4,856,650. Also, is known to include in the packet, along with iron, areaction promoter such as sodium chloride, and a water-absorbing agent,such as silica gel, as described in the U.S. Pat. No. 4,992,410. JapanLaid Open Patent Application No. 82-24634 (1982) discloses an oxygenabsorber composition comprising 100 parts by weight (pbw) iron powder, 2to 7 pbw ammonium chloride, 8 to 15 pbw aqueous acid solution and 20 to50 pbw of a slightly water soluble filler such as activated clay. JapanLaid Open Patent Application No. 79-158386 (1979) discloses an oxygenarresting composition comprising a metal, such as iron, copper or zinc,and optionally, a metal halide such as sodium chloride or zinc chlorideat a level of 0.001 to 100 pbw to 1 pbw of metal and a filler such asclay at a level of 0.01 to 100 pbw to 1 pbw of metal.

Although oxygen absorbent or scavenger materials used in packets canreact chemically with oxygen in the package, also sometimes referred toas “headspace oxygen”, they do not prevent external oxygen frompenetrating into the package. Therefore, it is common for packaging inwhich such packets are used to include additional protection such aswrappings or passive barrier films of the type described above. Thisadds to product costs. With many easy-to-prepare foods, anotherdifficulty with oxygen scavenger packets is that consumers maymistakenly open them and consume their contents together with the food.Moreover, the extra manufacturing step of placing a packet into acontainer can add to the cost of the product and slow production.Further, oxygen absorbent packets are not useful with liquid products.

In view of these disadvantages and limitation, it has been proposed toincorporate directly into the walls of a packaging article a so-called“active” oxygen absorber, i.e., one that reacts with oxygen. Becausesuch a packaging article is formulated to include a material that reactswith oxygen permeating its walls, the packaging is said to provide an“active-barrier” as distinguished from passive barrier films which blocktransmission of oxygen but do not react with it. Active-barrierpackaging is an attractive way to protect oxygen-sensitive productsbecause it not only can prevent oxygen from reaching the product fromthe outside but also can absorb oxygen present within a container. Oneapproach for obtaining active-barrier packaging is to incorporate amixture of an oxidizable metal (e.g., iron) and an electrolyte (e.g.,sodium chloride) into a suitable resin, melt process the result intomonolayer or multilayer sheets or films and form the resulting oxygenscavenger-containing sheets or films into rigid or flexible containersor other packaging articles or components. This type of active-barrieris disclosed in Japan Laid Open Patent Application No. 56-60642 (1981),directed to an oxygen-scavenging sheet composed of a thermoplastic resincontaining iron, zinc or copper and a metal halide. Disclosed resinsinclude polyethylene and polyethylene terephthalate. Sodium chloride isthe preferred metal halide. Component proportions are such that 1 to 500parts metal halide are present per 100 parts resin and 1 to 200 partsmetal halide are present per 100 part metal. Similarly, the U.S. Pat.No. 5,153,038 discloses plastic multilayer vessels of various layerstructures formed from a resin composition formed by incorporating anoxygen scavenger, and optionally a water absorbing agent, in a gasbarrier resin. The oxygen scavenger can be a metal powder such as iron,low valence metal oxides or reducing metal compounds. The oxygenscavenger can be used in combination with an assistant compound such asa hydroxide, carbonate, sulfite, thiosulfite, tertiary phosphate,secondary phosphate, organic acid salt or halide of an alkali metal oralkaline earth metal. The water absorbing agent can be an inorganic saltsuch as sodium chloride, calcium chloride, zinc chloride, ammoniumchloride, ammonium sulfate, sodium sulfate, magnesium sulfate, disodiumhydrogenphosphate, sodium dihydrogenphosphate, potassium carbonate orsodium nitrate. The oxygen scavenger can be present at 1 to 1000weight-% based on weight of the barrier resin. The water absorbing agentcan be present at 1 to 300 weight-% based on weight of the barrierresin.

One difficulty with scavenger systems incorporating an oxidizable metal(e.g., iron) and a metal halide (e.g., sodium chloride) into athermoplastic layer is the inefficiency of the oxidation reaction. Toobtain sufficient oxygen absorption in active-barrier packaging, highloadings of scavenger composition are often used. This typicallyrequires that sheets, films and the other packaging layer or wallstructures containing a scavenging composition be relatively thick.This, in turn, contributes to cost of packaging material and maypreclude attainment of thin packaging films having adequateoxygen-scavenging capabilities.

Another oxygen-scavenging composition, disclosed in the U.S. Pat. No.4,104,192, comprises a dithionite and at least one compound having waterof crystallization or water of hydration. Listed among these compoundsare various hydrated sodium salts, including carbonate, sulfate, sulfiteand phosphates; sodium pyrophosphate decahydrate is specificallymentioned. As disclosed in Table 1, Example 1 of the patent, sodiumpyrophosphate decahydrate was the least effective of the compoundstested. In addition, use of hydrate containing compounds may notsuitable in oxygen-scavenging resins that require high temperatureprocessing. The U.S. Pat. No. 5,744,056, U.S. Pat. No. 6,369,148 andU.S. Pat. No. 6,586,514 describe an oxygen scavenging compositioncomprising an oxidizable metal component, an electrolyte component, anda non-electrolytic acidifying component that is thermally stable atthermoplastic resin melt fabrication temperatures.

WO2006/089895 discloses a similar system wherein the electrolyticcomponent participating in the oxidation reaction is obtained byhydrolysis of a Lewis acid salt and/or its adducts. One difficulty withscavenger systems of this type is the relative inefficiency of theoxidation reaction within the polymer matrix. Indeed, the scavengercomposition must be employed usually at high loading, leading to cost,compatibility, transparency and color issues. In EP-A-1 423 456 theconcentration of the metal is limited to less than 0.25% in order toobtain a more transparent plastic object, limiting significantly itseffectiveness. Thus, while a variety of approaches to maintaining orreducing oxygen levels in packaged items have been advanced, thereremains a need for improved oxygen-scavenging composition and packagingmaterials utilizing the same.

An object of the present invention is therefore to provide improvedoxygen-scavenging compositions and packagings. Another object is toprovide low costs, oxygen-scavenging compositions of improvedefficiency. Another object is to provide oxygen scavenging compositionthat can be used effectively, even at relatively low levels, in a widerange of active-barrier packaging films and sheets, including laminatedand coextruded multilayer films and sheets. Another object is ti provideactive-barrier packaging containers that can increase the shelf-life ofoxygen-sensitive products by slowing the passage of external oxygen intothe container, by absorbing oxygen present inside the container or both.Other objects will be apparent to those skilled in the art.

It has been observed that the addition of non ionic surfactants likealkylpolyethylene glycol ethers from linear, saturated C₁₆-C₁₈ fattyalcohols; or saturated, predominantly unbranched C₁₃-C₅₀ oxo-alcohols;polypropylene glycols and polypropylene-block-polyethylene glycolcopolymers which are thermally stable at temperature generally used forprocessing thermoplastic resin, and used in combination withelectrolytes and non electrolytic acidifying components in addition ofoxidizable metal particles (such as those described in U.S. Pat. No.5,744,056, U.S. Pat. No. 6,369,148, U.S. Pat. No. 6,586,514, andWO2006/089895), specifically particles whose larger dimension iscomprised between 1000 μm and 10 μm, most preferably between 10 μm and300 μm, ad in particular in the range of 10 μm and 50 μm to increase thequantity of oxygen able to react with each unit of metal.

Thus the oxidation reaction occurs more readily and the overall oxygenscavenging performance can be accelerated. This greater reactivity canbe exploited, practically, either in order to achieve greater rates andamounts of reaction (greater scavenging ability and speed) or, byreducing the quantity of scavenging composition put in contact with thetarget environment, in order to achieve the same rates and amounts ofreaction with a plastic film or container even more clear andtransparent.

Thus, the present invention relates to an oxygen-scavenging composition,a composition comprising a polymeric resin and said oxygen-scavengingcomposition, an article containing said composition, a masterbatchcontaining said oxygen-scavenging composition and the use of saidoxygen-scavenging composition in food packaging.

Thus, the present invention relates to an oxygen-scavenging compositioncomprising

(I) an oxidizable metal component,

(II) an electrolyte component,

(III) a non-electrolytic, acidifying component, and

(IV) a non ionic surfactant component, preferably selected from thegroup consisting of alkyl polyethylene glycol ethers, polyethyleneglycols, polypropylene glycols, polypropylene glycol polyethylene glycolblock copolymers and polyethylene polyethylene glycol block copolymers.

An article containing said oxygen-scavenging composition, a masterbatchcontaining said oxygen-scavenging composition and the use of saidoxygen-scavenging composition in food packaging.

The oxidizable metal of the invention can be Al, Mg, Zn, Cu, Fe, Sn, Coor Mn, although Fe is preferred for the balance of cost and reactivity.Alloys or blends of such metals, or of such metals with othercomponents, are also suitable. The particles can be of any shape, suchas spherical, octahedral, cubic, in the form of rods or platelets and soon. They can be functionnalized for better dispersion in the polymericmatrix or for optimal reactivity. However, preferred metal particles arenot functionalized or stabilized by specific binding or interaction withpolymeric, organic or organometallic compounds impermeable to oxygentransport.

The sum of oxidizable metal, electrolyte, non-electrolytic acidifyingcomponent and non ionic surfactant can comprise from 5 to 50% of totalcomposition, the balance being polymer resin.

The weight ratio of electrolyte to non-electrolytic acidifying componentcan vary from 10/90 to 90/10. The sum of electrolyte andnon-electrolytic acidifying component can be 20 to 500 parts by weightper 100 parts metal.

In addition the weight ratio of non ionic surfactant to electrolyte canvary from 10/90 to 90/10. The sum of electrolyte and non ionicsurfactant can be 20 to 500 parts by weight per 100 parts metal.

The non-electrolytic, acidifying component includes variousnon-electrolytic organic and inorganic acids and their salts. Examplesof particular compounds include anhydrous citric acid, citric acidmonosodium salt, ammonium sulfate, magnesium sulfate, disodiumdihydrogen pyrophosphate, also known as sodium acid pyrophosphate(Na₂H₂P₂O₇), sodium metaphosphate, sodium trimetaphosphate, sodiumhexametaphosphate, citric acid disodium salt, ammonium phosphate,aluminum sulfate, nicotinic acid, aluminum ammonium sulfate, sodiumphosphate monobasic and aluminum potassium sulfate. Combinations of suchmaterials also can be used.

A particularly preferred non-electrolytic, acidifying componentcomprises as component (III) an alkali metal acid pyrophosphate or analkaline earth metal acid pyrophosphate and optionally in addition ascomponent (IIIa) an alkali metal dihydrogenphosphate (e.g. NaH₂PO₄) oran alkaline earth metal dihydrogenphosphate. Preferably, at least 1part, in particular 1 to 10 parts, by weight of component (IIIa) per 100parts by weight of component (III) is used.

Particularly preferred non ionic surfactants are alkylpolyethyleneglycol ethers preferably made from a linear, saturated C₁₆-C₁₈ fattyalcohol, having the formula RO(CH₂CH₂O)_(x)H, (1) wherein R is a linearsaturated C₁₆-C₁₈ fatty alcohol residue and x is a number of 11 to 80,preferably 11, 18, 25, 50 and 80 (Lutensol®AT types).

Likewise preferred are non ionic surfactants of the formula (1), whereinR is a C₁₃-C₁₅ saturated predominantly unbranched oxo alcohol residueand x is a number of 3 to 30, preferably 3, 4, 5, 7, 8, 10, 11 and 30(Lutensol® AO types).

Likewise preferred as non ionic surfactants are polyethylene orpolypropylene glycols of the formula

having a molecular weight in the range of 200 to 12000 g/mol (Pluriol®Etypes and Pluriol®P types).

Likeweise preferred as non ionic surfactants are block copolymers inwhich the central polypropylene glycol unit is flanked by twopolyethylene units and which have the formula

and a molecular weight in the range of 900 to 3500 g/mol (Pluronic®PEtypes).

Preferred compounds of formula (4) have 10 to 80%, in particular 40 to80% by weight of polyethylene glycol in the molecule. The sum of m+n+zis for example a number of 15 to 80.

A particularly preferred oxygen-scavenging composition according to thepresent invention comprises

(I) an oxidizable metal component,

(II) an electrolyte component selected from the group consisting ofNaCl, KCl and CaCl₂,

(III) a non-electrolytic, acidifying component, preferably an alkalimetal acid pyrophosphate or an alkaline earth metal acid pyrophosphate,and

(IV) a non ionic surfactant component selected from the group containingalkylpolyethylene glycol ethers preferably made from a linear, saturatedC₁₆-C₁₈ fatty alcohol, having the formula RO(CH₂CH₂O)_(x)H, (1) whereinR is a linear saturated C₁₆-C₁₈ fatty alcohol residue and x is a numberof 11 to 80, preferably 11, 18, 25, 50 and 80.

A further particularly preferred oxygen-scavenging composition accordingto the present invention comprises

(I) an oxidizable metal component,

(II) an electrolyte component selected from the group consisting ofNaCl, KCl and CaCl₂,

(III) a non-electrolytic, acidifying component, preferably an alkalimetal acid pyrophosphate or an alkaline earth metal acid pyrophosphate,and

(IV) a non ionic surfactant component selected from the group containingalkylpolyethylene glycol ethers preferably made from a linear, saturatedC₁₃-C₁₅ fatty alcohol, having the formula RO(CH₂CH₂O)_(x)H, (1) whereinR is a C₁₃-C₁₅ saturated predominantly unbranched oxo alcohol residueand x is a number of 3 to 30, preferably 3, 4, 5, 7, 8, 10, 11 and 30.

A further particularly preferred oxygen-scavenging composition accordingto the present invention comprises

(I) an oxidizable metal component,

(II) an electrolyte component selected from the group consisting ofNaCl, KCl and CaCl₂,

(III) a non-electrolytic, acidifying component, preferably an alkalimetal acid pyrophosphate or an alkaline earth metal acid pyrophosphate,and

(IV) a non ionic surfactant component selected from the group containingpolyethylene or polypropylene glycols of formulas HO

CH₂—CH₂—O

_(n)H (2) and

having a molecular weight in the range of 200 to 12000 g/mol.

A further particularly preferred oxygen-scavenging composition accordingto the present invention comprises

(I) an oxidizable metal component,

(II) an electrolyte component selected from the group consisting ofNaCl, KCl and CaCl₂,

(III) a non-electrolytic, acidifying component, preferably an alkalimetal acid pyrophosphate or an alkaline earth metal acid pyrophosphate,and

(IV) a non ionic surfactant component selected from the group containingblock copolymers in which the central polypropylene glycol unit isflanked by two polyethylene units and which have the formula

and a molecular weight in the range of 900 to 3500 g/mol.

A particularly preferred embodiment of the present invention relates toan oxygen-scavenging composition wherein

(I) the oxidizable metal component is iron,

(II) the electrolyte component is NaCl,

(III) the non-electrolytic, acidifying component is Na₂H₂P₂O₇, and

(IV) the non ionic surfactant component is selected from the groupconsisting of alkyl polyethylene glycol ethers, polyethylene glycols,polypropylene glycols, polypropylene glycol polyethylene glycol blockcopolymers and polyethylene polyethylene glycol block copolymers;and optionally as component (IIIa) NaH₂PO₄.

The components of the present oxygen-scavenging compositions are presentin proportions effective to provide oxygen-scavenging effects.Preferably, at least 1 part by weight of electrolyte component plusacidifying component is present per 100 parts by weight of oxidizablemetal component, with the weight ratio of electrolyte component tonon-electrolytic, acidifying component of e.g. 99:1 to 1:99, inparticular 10:90 to 90:10. More preferably, at least about 10 parts ofelectrolyte plus non-electrolytic, acidifying components are present per100 parts of oxidizable metal component to promote efficient usage ofthe latter for reaction with oxy-gen. In order to achieve anadvantageous combination of oxidation efficiency, low cost and ease ofprocessing and handling, 20 to 500, in particular 30 to 130 parts ofelectrolyte plus non-electrolytic, acidifying components per 100 partsof metal component are most preferred.

According to a preferred embodiment, the oxygen-scavenging compositionmay additionally contain a water-absorbant binder to further enhanceoxidation efficiency of the oxidizable metal. The binder can serve toprovide additional moisture which enhances oxidation of the metal in thepresence of the promoter compounds. Water-absorbing binders suitable foruse generally include materials that absorb at least about 5 percent oftheir own weight in water and are chemically inert. Examples of suitablebinders include diatomaceous earth, boehmite, kaolin clay, bentoniteclay, acid clay, activated clay, zeolite, molecular sieves, talc,calcined vermiculite, activated carbon, graphite, carbon black, and thelike. It is also contemplated to utilize organic binders, examplesincluding various water absorbent polymers are disclosed inEP-A-428,736. Mixtures of such binders can also be employed. Preferredbinders are bentonite clay, kaolin clay, and silica gel.

If present, the water-absorbent binder is preferably used in an amountof e.g. 5 to 100 parts per 100 parts of metal. When a binder componentis used in compositions compounded into plastics, the binder mostpreferably is present in an amount of 10 to 50 parts per 100 parts ofmetal to enhance oxidation efficiency at loading levels low enough toensure ease of processing.

Another embodiment of the present invention relates to anoxygen-scavenging composition as defined above and containing optionallya conventional additive and further as component (V) an additionalpolymeric resin different from the inventive non ionic surfactant (IV).

Examples of such polymeric resins are:

1. Polymers of monoolefins and diolefins, for example polypropylene,polyisobutylene, polybut-1-ene, poly-4-methylpent-1-ene,polyvinylcyclohexane, polyisoprene or polybutadiene, as well as polymersof cycloolefins, for instance of cyclopentene or norbornene,polyethylene (which optionally can be crosslinked), for example highdensity polyethylene (HDPE), high density and high molecular weightpolyethylene (HDPEHMW), high density and ultrahigh molecular weightpolyethylene (HDPE-UHMW), medium density polyethylene (MDPE), lowdensity polyethylene (LDPE), linear low density polyethylene (LLDPE),(VLDPE) and (ULDPE).Polyolefins, i.e. the polymers of monoolefins exemplified in thepreceding paragraph, preferably polyethylene and polypropylene, can beprepared by different, and especially by the following, methods:a) radical polymerisation (normally under high pressure and at elevatedtemperature).b) catalytic polymerisation using a catalyst that normally contains oneor more than one metal of groups IVb, Vb, VIb or VIII of the PeriodicTable. These metals usually have one or more than one ligand, typicallyoxides, halides, alcoholates, esters, ethers, amines, alkyls, alkenylsand/or aryls that may be either π- or σ-coordinated. These metalcomplexes may be in the free form or fixed on substrates, typically onactivated magnesium chloride, titanium(III) chloride, alumina or siliconoxide. These catalysts may be soluble or insoluble in the polymerisationmedium. The catalysts can be used by themselves in the polymerisation orfurther activators may be used, typically metal alkyls, metal hydrides,metal alkyl halides, metal alkyl oxides or metal alkyloxanes, saidmetals being elements of groups Ia, IIa and/or IIIa of the PeriodicTable. The activators may be modified conveniently with further ester,ether, amine or silyl ether groups. These catalyst systems are usuallytermed Phillips, Standard Oil Indiana, Ziegler (Natta), TNZ (DuPont),metallocene or single site catalysts (SSC).2. Mixtures of the polymers mentioned under 1), for example mixtures ofpolypropylene with polyisobutylene, polypropylene with polyethylene (forexample PP/HDPE, PP/LDPE) and mixtures of different types ofpolyethylene (for example LDPE/HDPE).3. Copolymers of monoolefins and diolefins with each other or with othervinyl monomers, for example ethylene/propylene copolymers, linear lowdensity polyethylene (LLDPE) and mixtures thereof with low densitypolyethylene (LDPE), propylene/but-1-ene copolymers,propylene/isobutylene copolymers, ethylene/but-1-ene copolymers,ethylene/hexene copolymers, ethylene/methylpentene copolymers,ethylene/heptene copolymers, ethylene/octene copolymers,ethylene/vinylcyclohexane copolymers, ethylene/cycloolefin copolymers(e.g. ethylene/norbornene like COC), ethylene/1-olefins copolymers,where the 1-olefin is generated in-situ; propylene/butadiene copolymers,isobutylene/isoprene copolymers, ethylene/vinylcyclohexene copolymers,ethylene/alkyl acrylate copolymers, ethylene/alkyl methacrylatecopolymers, ethylene/vinyl acetate copolymers or ethylene/acrylic acidcopolymers and their salts (ionomers) as well as terpolymers of ethylenewith propylene and a diene such as hexadiene, dicyclopentadiene orethylidene-norbornene; and mixtures of such copolymers with one anotherand with polymers mentioned in 1) above, for examplepolypropylene/ethylene-propylene copolymers, LDPE/ethylene-vinyl acetatecopolymers (EVA), LDPE/ethylene-acrylic acid copolymers (EAA),LLDPE/EVA, LLDPE/EAA and alternating or random polyalkylene/carbonmonoxide copolymers and mixtures thereof with other polymers, forexample polyamides.4. Hydrocarbon resins (for example C₅-C₉) including hydrogenatedmodifications thereof (e.g. tackifiers) and mixtures of polyalkylenesand starch.Homopolymers and copolymers from 1.)-4.) may have any stereostructureincluding syndiotactic, isotactic, hemi-isotactic or atactic; whereatactic polymers are preferred. Stereoblock polymers are also included.5. Polystyrene, poly(p-methylstyrene), poly(α-methylstyrene).6. Aromatic homopolymers and copolymers derived from vinyl aromaticmonomers including styrene, α-methylstyrene, all isomers of vinyltoluene, especially pvinyltoluene, all isomers of ethyl styrene, propylstyrene, vinyl biphenyl, vinyl naphthalene, and vinyl anthracene, andmixtures thereof. Homopolymers and copolymers may have anystereostructure including syndiotactic, isotactic, hemi-isotactic oratactic; where atactic polymers are preferred. Stereoblock polymers arealso included.6a. Copolymers including aforementioned vinyl aromatic monomers andcomonomers selected from ethylene, propylene, dienes, nitriles, acids,maleic anhydrides, maleimides, vinyl acetate and vinyl chloride oracrylic derivatives and mixtures thereof, for example styrene/butadiene,styrene/acrylonitrile, styrene/ethylene (interpolymers), styrene/alkylmethacrylate, styrene/butadiene/alkyl acrylate, styrene/butadiene/alkylmethacrylate, styrene/maleic anhydride, styrene/acrylonitrile/methylacrylate; mixtures of high impact strength of styrene copolymers andanother polymer, for example a polyacrylate, a diene polymer or anethylene/propylene/diene terpolymer; and block copolymers of styrenesuch as styrene/butadiene/styrene, styrene/isoprene/styrene,styrene/ethylene/butylene/styrene or styrene/ethylene/propylene/styrene.6b. Hydrogenated aromatic polymers derived from hydrogenation ofpolymers mentioned under 6.), especially includingpolycyclohexylethylene (PCHE) prepared by hydrogenating atacticpolystyrene, often referred to as polyvinylcyclohexane (PVCH).6c. Hydrogenated aromatic polymers derived from hydrogenation ofpolymers mentioned under 6a.).Homopolymers and copolymers may have any stereostructure includingsyndiotactic, isotactic, hemi-isotactic or atactic; where atacticpolymers are preferred. Stereoblock polymers are also included.7. Graft copolymers of vinyl aromatic monomers such as styrene orα-methylstyrene, for example styrene on polybutadiene, styrene onpolybutadiene-styrene or polybutadiene-acrylonitrile copolymers; styreneand acrylonitrile (or methacrylonitrile) on polybutadiene; styrene,acrylonitrile and methyl methacrylate on polybutadiene; styrene andmaleic anhydride on polybutadiene; styrene, acrylonitrile and maleicanhydride or maleimide on polybutadiene; styrene and maleimide onpolybutadiene; styrene and alkyl acrylates or methacrylates onpolybutadiene; styrene and acrylonitrile on ethylene/propylene/dieneterpolymers; styrene and acrylonitrile on polyalkyl acrylates orpolyalkyl methacrylates, styrene and acrylonitrile on acrylate/butadienecopolymers, as well as mixtures thereof with the copolymers listed under6), for example the copolymer mixtures known as ABS, MBS, ASA or AESpolymers.8. Halogen-containing polymers such as polychloroprene, chlorinatedrubbers, chlorinated and brominated copolymer of isobutylene-isoprene(halobutyl rubber), chlorinated or sulfochlorinated polyethylene,copolymers of ethylene and chlorinated ethylene, epichlorohydrin homo-and copolymers, especially polymers of halogen-containing vinylcompounds, for example polyvinyl chloride, polyvinylidene chloride,polyvinyl fluoride, polyvinylidene fluoride, as well as copolymersthereof such as vinyl chloride/vinylidene chloride, vinyl chloride/vinylacetate or vinylidene chloride/vinyl acetate copolymers.9. Polymers derived from α,β-unsaturated acids and derivatives thereofsuch as polyacrylates and polymethacrylates; polymethyl methacrylates,polyacrylamides and polyacrylonitriles, impact-modified with butylacrylate.10. Copolymers of the monomers mentioned under 9) with each other orwith other unsaturated monomers, for example acrylonitrile/butadienecopolymers, acrylonitrile/alkyl acrylate copolymers,acrylonitrile/alkoxyalkyl acrylate or acrylonitrile/vinyl halidecopolymers or acrylonitrile/alkyl methacrylate/butadiene terpolymers.11. Polymers derived from unsaturated alcohols and amines or the acylderivatives or acetals thereof, for example polyvinyl alcohol, polyvinylacetate, polyvinyl stearate, polyvinyl benzoate, polyvinyl maleate,polyvinyl butyral, polyallyl phthalate or polyallyl melamine; as well astheir copolymers with olefins mentioned in 1) above.12. Homopolymers and copolymers of cyclic ethers such as polyethyleneoxide, polypropylene oxide or copolymers thereof with bisglycidylethers.13. Polyacetals such as polyoxymethylene and those polyoxymethyleneswhich contain ethylene oxide as a comonomer; polyacetals modified withthermoplastic polyurethanes, acrylates or MBS.14. Polyphenylene oxides and sulfides, and mixtures of polyphenyleneoxides with styrene polymers or polyamides.15. Polyurethanes derived from hydroxyl-terminated polyethers,polyesters or polybutadienes on the one hand and aliphatic or aromaticpolyisocyanates on the other, as well as precursors thereof.16. Polyamides and copolyamides derived from diamines and dicarboxylicacids and/or from aminocarboxylic acids or the corresponding lactams,for example polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12,4/6, 12/12, polyamide 11, polyamide 12, aromatic polyamides startingfrom m-xylene diamine and adipic acid; polyamides prepared fromhexamethylenediamine and isophthalic or/and terephthalic acid and withor without an elastomer as modifier, for examplepoly-2,4,4,-trimethylhexamethylene terephthalamide or poly-m-phenyleneisophthalamide; and also block copolymers of the aforementionedpolyamides with polyolefins, olefin copolymers, ionomers or chemicallybonded or grafted elastomers; as well as polyamides or copolyamidesmodified with EPDM or ABS; and polyamides condensed during processing(RIM polyamide systems).17. Polyureas, polyimides, polyamide-imides, polyetherimids,polyesterimids, polyhydantoins and polybenzimidazoles.18. Polyesters derived from dicarboxylic acids and diols and/or fromhydroxycarboxylic acids or the corresponding lactones, for examplepolyethylene terephthalate, polybutylene terephthalate,poly-1,4-dimethylolcyclohexane terephthalate, polyalkylene naphthalate(PAN) and polyhydroxybenzoates, as well as block copolyether estersderived from hydroxyl-terminated polyethers; and also polyestersmodified with polycarbonates or MBS.19. Polycarbonates and polyester carbonates.20. Polyketones.21. Polysulfones, polyether sulfones and polyether ketones.22. Crosslinked polymers derived from aldehydes on the one hand andphenols, ureas and melamines on the other hand, such asphenol/formaldehyde resins, urea/formaldehyde resins andmelamine/formaldehyde resins.23. Drying and non-drying alkyd resins.24. Unsaturated polyester resins derived from copolyesters of saturatedand unsaturated dicarboxylic acids with polyhydric alcohols and vinylcompounds as crosslinking agents, and also halogen-containingmodifications thereof of low flammability.25. Crosslinkable acrylic resins derived from substituted acrylates, forexample epoxy acrylates, urethane acrylates or polyester acrylates.26. Alkyd resins, polyester resins and acrylate resins crosslinked withmelamine resins, urea resins, isocyanates, isocyanurates,polyisocyanates or epoxy resins.27. Crosslinked epoxy resins derived from aliphatic, cycloaliphatic,heterocyclic or aromatic glycidyl compounds, e.g. products of diglycidylethers of bisphenol A and bisphenol F, which are crosslinked withcustomary hardeners such as anhydrides or amines, with or withoutaccelerators.28. Natural polymers such as cellulose, rubber, gelatin and chemicallymodified homologous derivatives thereof, for example cellulose acetates,cellulose propionates and cellulose butyrates, or the cellulose etherssuch as methyl cellulose; as well as rosins and their derivatives.29. Blends of the aforementioned polymers (polyblends), for examplePP/EPDM, Polyamide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS,PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic PUR,PC/thermoplastic PUR, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA 6.6 andcopolymers, PA/HDPE, PA/PP, PA/PPO, PBT/PC/ABS or PBT/PET/PC.30. Naturally occurring and synthetic organic materials which are puremonomeric compounds or mixtures of such compounds, for example mineraloils, animal and vegetable fats, oil and waxes, or oils, fats and waxesbased on synthetic esters (e.g. phthalates, adipates, phosphates ortrimellitates) and also mixtures of synthetic esters with mineral oilsin any weight ratios, typically those used as spinning compositions, aswell as aqueous emulsions of such materials.31. Aqueous emulsions of natural or synthetic rubber, e.g. natural latexor latices of carboxylated styrene/butadiene copolymers.

Any suitable polymeric resin of the above list into which an effectiveamount of the oxygen-scavenging composition of this invention can beincorporated and that can be formed into a laminar configuration, suchas film, sheet or a wall structure, can be used as the plastic resin inthe compositions according to this aspect of the invention.Thermoplastic and thermoset resins which can be used are for examplenylon 6, nylon 66 and nylon 612, linear and branched polyesters, such aspolyethylene terephthalate, polybutylene terephthalate and polyethylenenaphthalate, polystyrenes, polycarbonate, polymers of unsubstituted,substituted or functionalized olefins such as polyvinyl chloride,polyvinylidene dichloride, polyacrylamide, polyacrylonitrile, polyvinylacetate, polyacrylic acid, polyvinyl methyl ether, ethylene vinylacetate copolymer, ethylene methyl acrylate copolymer, polyethylene,polypropylene, ethylene-propylene copolymers, poly(1-hexene),poly(4-methyl-1-pentene), poly(1-butene), poly(3-methyl-1-butene),poly(3-phenyl-1-propene) and poly(vinylcyclohexane).

Preferred polymers are in particular thermoplastic resins having oxygenpermeation coefficients greater than 2×10⁻¹² cm³ cm cm⁻² sec⁻¹ cm⁻¹ Hgas measured at a temperature of 20° C. and a relative humidity of 0%because such resins are relatively inexpensive, easily formed intopackaging structures and, when used with the invented oxygen-scavengingcomposition, can provide a high degree of active barrier protection tooxygen-sensitive products. Examples of these include polyethyleneterephthalate and polyalpha-olefin resins such as high, low and linearlow density polyethylene and polypropylene. Even relatively low levelsof oxygen-scavenging composition, e.g. 5 to 15 parts per 100 partsresin, can provide a high degree of oxygen barrier protection to suchresins. Among these preferred resins, permeability to oxygen increasesin the order polyethylene terephthalate, polypropylene, high densitypolyethylene, linear low density polyethylene and low densitypolyethylene, other things being equal. Accordingly, for such polymericresins, oxygen scavenger loadings for achieving a given level of oxygenbarrier effectiveness increase in like order, other things being equal.

In selecting a thermoplastic resin for use or compounding with theoxygen-scavenging composition of the invention, the presence of residualantioxidant compounds in the resin can be detrimental to oxygenabsorption effectiveness. Phenol-type antioxidants and phosphite-typeantioxidants are commonly used by polymer manufacturers for the purposeof enhancing thermal stability of resins and fabricated productsobtained therefrom. Specific examples of these residual antioxidantcompounds include materials such as butylated hydroxytoluene,tetrakis(methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)methane andtriisooctyl phosphite. Such antioxidants are not to be confused with theoxygen-scavenger components utilized in the present invention.Generally, oxygen absorption of the scavenger compositions of thepresent invention is improved as the level of residual antioxidantcompounds is reduced. Thus, commercially available resins containing lowlevels of phenol-type or phosphite-type antioxidants, preferably lessthan about 1600 ppm, and most preferably less than about 800 ppm, byweight of the resin, are preferred (although not required) for use inthe present invention. Examples are Dow Chemical Dowlex 2032® linear lowdensity polyethylene (LLDPE); Union Carbide GRSN 7047® LLDPE; GoodyearPET “Traytuf” 9506®; and Eastman PETG 6763®. Measurement of the amountof residual antioxidant can be performed using high pressure liquidchromatography.

If desired, in addition one or more of the following conventionaladditives might be used in combination with the oxygen scavengerformulation; the list includes for example antioxidants, UV absorbersand/or further light stabilizers such as e.g.:

-   1. Alkylated monophenols, for example    2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol,    2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol,    2,6-di-tert-butyl-4-isobutylphenol,    2,6-dicyclopentyl-4-methylphenol,    2-(α-methylcyclohexyl)-4,6-dimethylphenol,    2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol,    2,6-di-tert-butyl-4-methoxymethylphenol, nonylphenols which are    linear or branched in the side chains, for example,    2,6-di-nonyl-4-methylphenol,    2,4-dimethyl-6-(1′-methylundec-1′-yl)phenol,    2,4-dimethyl-6-(1′-methylheptadec-1′-yl)phenol,    2,4-dimethyl-6-(1′-methyltridec-1′-yl)phenol and mixtures thereof.-   2. Alkylthiomethylphenols, for example    2,4-dioctylthiomethyl-6-tert-butylphenol,    2,4-dioctylthiomethyl-6-methylphenol,    2,4-dioctylthiomethyl-6-ethylphenol,    2,6-didodecylthiomethyl-4-nonylphenol.-   3. Hydroquinones and alkylated hydroquinones, for example    2,6-di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butylhydroquinone,    2,5-di-tert-amylhydroquinone, 2,6-diphenyl-4-octadecyloxyphenol,    2,6-di-tert-butylhydroquinone, 2,5-di-tert-butyl-4-hydroxyanisole,    3,5-di-tert-butyl-4-hydroxyanisole,    3,5-di-tert-butyl-4-hydroxyphenyl stearate,    bis(3,5-di-tert-butyl-4-hydroxyphenyl) adipate.-   4. Tocopherols, for example α-tocopherol, β-tocopherol,    γ-tocopherol, δ-tocopherol and mixtures thereof (vitamin E).-   5. Hydroxylated thiodiphenyl ethers, for example    2,2′-thiobis(6-tert-butyl-4-methylphenol),    2,2′-thiobis(4-octylphenol),    4,4′-thiobis(6-tert-butyl-3-methylphenol),    4,4′-thiobis(6-tert-butyl-2-methylphenol),    4,4′-thiobis(3,6-di-sec-amylphenol),    4,4′-bis(2,6-dimethyl-4-hydroxyphenyl)disulfide.-   6. Alkylidenebisphenols, for example    2,2′-methylenebis(6-tert-butyl-4-methylphenol),    2,2′-methylenebis(6-tert-butyl-4-ethylphenol),    2,2′-methylenebis[4-methyl-6-(α-methylcyclohexyl)phenol],    2,2′-methylenebis(4-methyl-6-cyclohexylphenol),    2,2′-methylenebis(6-nonyl-4-methylphenol),    2,2′-methylenebis(4,6-di-tert-butylphenol),    2,2′-ethylidenebis(4,6-di-tert-butylphenol),    2,2′-ethylidenebis(6-tert-butyl-4-isobutylphenol),    2,2′-methylenebis[6-(α-methylbenzyl)-4-nonylphenol],    2,2′-methylenebis[6-(α,α-dimethylbenzyl)-4-nonylphenol],    4,4′-methylenebis(2,6-di-tert-butylphenol),    4,4′-methylenebis(6-tert-butyl-2-methylphenol),    1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,    2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol,    1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,    1,1-bis(5-tert-butyl-4-hydroxy-2-methyl-phenyl)-3-n-dodecylmercaptobutane,    ethylene glycol    bis[3,3-bis(3′-tert-butyl-4′-hydroxyphenyl)butyrate],    bis(3-tert-butyl-4-hydroxy-5-methyl-phenyl)dicyclopentadiene,    bis[2-(3′-tert-butyl-2′-hydroxy-5′-methylbenzyl)-6-tert-butyl-4-methylphenyl]terephthalate,    1,1-bis-(3,5-dimethyl-2-hydroxyphenyl)butane,    2,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propane,    2,2-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-4-n-dodecylmercaptobutane,    1,1,5,5-tetra-(5-tert-butyl-4-hydroxy-2-methylphenyl)pentane.-   7. O-, N- and S-benzyl compounds, for example    3,5,3′,5′-tetra-tert-butyl-4,4′-dihydroxydibenzyl ether,    octadecyl-4-hydroxy-3,5-dimethylbenzylmercaptoacetate,    tridecyl-4-hydroxy-3,5-di-tert-butylbenzylmercaptoacetate,    tris(3,5-di-tert-butyl-4-hydroxybenzyl)amine,    bis(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)dithioterephthalate,    bis(3,5-di-tert-butyl-4-hydroxybenzyl)sulfide,    isooctyl-3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate.-   8. Hydroxybenzylated malonates, for example    dioctadecyl-2,2-bis(3,5-di-tert-butyl-2-hydroxybenzyl)malonate,    di-octadecyl-2-(3-tert-butyl-4-hydroxy-5-methylbenzyl)malonate,    di-dodecylmercaptoethyl-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate,    bis[4-(1,1,3,3-tetramethylbutyl)phenyl]-2,2-bis(3,5-di-tert-butyl-4-hydroxybenzyl)malonate.-   9. Aromatic hydroxybenzyl compounds, for example 1,    3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene,    1,4-bis(3,5-di-tert-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzene,    2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)phenol.-   10. Triazine compounds, for example    2,4-bis(octylmercapto)-6-(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,    2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyanilino)-1,3,5-triazine,    2-octylmercapto-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,3,5-triazine,    2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenoxy)-1,2,3-triazine,    1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,    1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate,    2,4,6-tris(3,5-di-tert-butyl-4-hydroxyphenylethyl)-1,3,5-triazine,    1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hexahydro-1,3,5-triazine,    1,3,5-tris(3,5-dicyclohexyl-4-hydroxybenzyl)isocyanurate.-   11. Benzylphosphonates, for example    dimethyl-2,5-di-tert-butyl-4-hydroxybenzylphosphonate,    diethyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,    dioctadecyl-3,5-di-tert-butyl-4-hydroxybenzylphosphonate,    dioctadecyl-5-tert-butyl-4-hydroxy-3-methylbenzylphosphonate, the    calcium salt of the monoethyl ester of    3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.-   12. Acylaminophenols, for example 4-hydroxylauranilide,    4-hydroxystearanilide, octyl    N-(3,5-di-tert-butyl-4-hydroxyphenyl)carbamate.-   13. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid    with mono- or polyhydric alcohols, e.g. with methanol, ethanol,    n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,    1,2-propanediol, ethylene glycol, neopentyl glycol, thiodiethylene    glycol, diethylene glycol, triethylene glycol, pentaerythritol,    tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,    3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,    trimethylolpropane,    4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.-   14. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionic    acid with mono- or polyhydric alcohols, e.g. with methanol, ethanol,    n-octanol, i-octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol,    ethylene glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene    glycol, diethylene glycol, triethylene glycol, pentaerythritol,    tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,    3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,    trimethylolpropane,    4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane;    3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane.-   15. Esters of β-(3,5-dicyclohexyl-4-hydroxyphenyl)propionic acid    with mono- or polyhydric alcohols, e.g. with methanol, ethanol,    octanol, octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene    glycol, 1,2-propanediol, neopentyl glycol, thiodiethylene glycol,    diethylene glycol, triethylene glycol, pentaerythritol,    tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,    3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,    trimethylolpropane,    4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.-   16. Esters of 3,5-di-tert-butyl-4-hydroxyphenyl acetic acid with    mono- or polyhydric alcohols, e.g. with methanol, ethanol, octanol,    octadecanol, 1,6-hexanediol, 1,9-nonanediol, ethylene glycol,    1,2-propanediol, neopentyl glycol, thiodiethylene glycol, diethylene    glycol, triethylene glycol, pentaerythritol,    tris(hydroxyethyl)isocyanurate, N,N′-bis(hydroxyethyl)oxamide,    3-thiaundecanol, 3-thiapentadecanol, trimethylhexanediol,    trimethylolpropane,    4-hydroxymethyl-1-phospha-2,6,7-trioxabicyclo[2.2.2]octane.-   17. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid    e.g.    N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionypexamethylenediamide,    N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)trimethylenediamide,    N,N′-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyphydrazide,    N,N′-bis[2-(3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyloxy)ethyl]oxamide    (Naugard® XL-1, supplied by Uniroyal).-   18. Ascorbic acid (vitamin C)-   19. Aminic antioxidants, for example    N,N′-di-isopropyl-p-phenylenediamine,    N,N′-di-sec-butyl-p-phenylenediamine,    N,N′-bis(1,4-dimethylpentyl)-p-phenylenediamine,    N,N′-bis(1-ethyl-3-methylpentyl)-p-phenylenediamine,    N,N′-bis(1-methylheptyl)-p-phenylenediamine,    N,N′-dicyclohexyl-p-phenylenediamine,    N,N′-diphenyl-p-phenylenediamine,    N,N′-bis(2-naphthyl)-p-phenylenediamine,    N-isopropyl-N′-phenyl-p-phenylenediamine,    N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine,    N-(1-methylheptyl)-N′-phenyl-p-phenylenediamine,    N-cyclohexyl-N′-phenyl-p-phenylenediamine,    4-(p-toluenesulfamoyl)diphenylamine,    N,N′-dimethyl-N,N′-di-secbutyl-p-phenylenediamine, diphenylamine,    N-allyldiphenylamine, 4-isopropoxydiphenylamine,    N-phenyl-1-naphthylamine, N-(4-tert-octylphenyl)-1-naphthylamine,    N-phenyl-2-naphthylamine, octylated diphenylamine, for example    p,p′-di-tert-octyldiphenylamine, 4-n-butylaminophenol,    4-butyrylaminophenol, 4-nonanoylaminophenol,    4-dodecanoylaminophenol, 4-octadecanoylaminophenol,    bis(4-methoxyphenyl)amine,    2,6-di-tert-butyl-4-dimethylaminomethylphenol,    2,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane,    N,N,N′,N′-tetramethyl-4,4′-diaminodiphenylmethane,    1,2-bis[(2-methylphenyl)amino]ethane, 1,2-bis(phenylamino)propane,    (o-tolyl)biguanide, bis[4-(1′,3′-dimethylbutyl)phenyl]amine,    tert-octylated N-phenyl-1-naphthylamine, a mixture of mono- and    dialkylated tert-butyl/tert-octyldiphenylamines, a mixture of mono-    and dialkylated nonyldiphenylamines, a mixture of mono- and    dialkylated dodecyldiphenylamines, a mixture of mono- and    dialkylated isopropyl/isohexyldiphenylamines, a mixture of mono- and    dialkylated tert-butyldiphenylamines,    2,3-dihydro-3,3-di-methyl-4H-1,4-benzothiazine, phenothiazine, a    mixture of mono- and dialkylated tert-butyl/tertoctylphenothiazines,    a mixture of mono- and dialkylated tert-octyl-phenothiazines,    N-allylphenothiazine, N,N,N′,N′-tetraphenyl-1,4-diaminobut-2-ene.-   20. 2-(2′-Hydroxyphenyl)benzotriazoles, for example    2-(2′-hydroxy-5′-methylphenyl)benzotriazole,    2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)benzotriazole,    2-(5′-tert-butyl-2′-hydroxyphenyl)benzotriazole,    2-(2′-hydroxy-5′-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole,    2-(3′,5′-di-tert-butyl-2′-hydroxyphenyl)-5-chloro-benzotriazole,    2-(3′-tert-butyl-2′-hydroxy-5′-methylphenyl)-5-chloro-benzotriazole,    2-(3′-sec-butyl-5′-tert-butyl-2′-hydroxyphenyl)benzotriazole,    2-(2′-hydroxy-4′-octyloxyphenyl)benzotriazole,    2-(3′,5′-di-tert-amyl-2′-hydroxyphenyl)benzotriazole,    2-(3′,5′-bis-(α,α-dimethylbenzyl)-2′-hydroxyphenyl)benzotriazole,    2-(3′-tert-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole,    2-(3′-tert-butyl-5′-[2-(2-ethylhexyloxy)-carbonylethyl]-2′-hydroxyphenyl)-5-chloro-benzotriazole,    2-(3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole,    2-(3′-tert-butyl-2′-hydroxy-5′-(2-methoxycarbonylethyl)phenyl)benzotriazole,    2-(3′-tert-butyl-2′-hydroxy-5′-(2-octyloxycarbonylethyl)phenyl)benzotriazole,    2-(3′-tert-butyl-5′-[2-(2-ethylhexyloxy)carbonylethyl]-2′-hydroxyphenyl)benzotriazole,    2-(3′-dodecyl-2′-hydroxy-5′-methylphenyl)benzotriazole,    2-(3′-tert-butyl-2′-hydroxy-5′-(2-isooctyloxycarbonylethyl)phenylbenzotriazole,    2,2′-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-benzotriazole-2-ylphenol];    the transesterification product of    2-[3′-tert-butyl-5′-(2-methoxycarbonylethyl)-2′-hydroxyphenyl]-2H-benzotriazole    with polyethylene glycol 300; [R—CH₂CH₂—COO—CH₂CH₂    ₂, where R=3′-tert-butyl-4′-hydroxy-5′-2H-benzotriazol-2-ylphenyl,    2-[2′-hydroxy-3′-(α,α-dimethylbenzyl)-5′-(1,1,3,3-tetramethylbutyl)-phenyl]benzotriazole;    2-[2′-hydroxy-3′-(1,1,3,3-tetramethylbutyl)-5′-(α,α-dimethylbenzyl)-phenyl]benzotriazole.-   21. 2-Hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy,    4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy,    4,2′,4′-trihydroxy and 2′-hydroxy-4,4′-dimethoxy derivatives.-   22. Esters of substituted and unsubstituted benzoic acids, for    example 4-tert-butylphenyl salicylate, phenyl salicylate,    octylphenyl salicylate, dibenzoyl resorcinol,    bis(4-tert-butylbenzoyl)resorcinol, benzoyl resorcinol,    2,4-di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate,    hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl    3,5-di-tert-butyl-4-hydroxybenzoate,    2-methyl-4,6-di-tert-butylphenyl    3,5-di-tert-butyl-4-hydroxybenzoate.-   23. Acrylates, for example ethyl α-cyano-β,β-diphenylacrylate,    isooctyl α-cyano-β,β-diphenylacrylate, methyl    α-carbomethoxycinnamate, methyl α-cyano-β-methyl-pmethoxycinnamate,    butyl α-cyano-β-methyl-p-methoxy-cinnamate, methyl    α-carbomethoxy-p-methoxycinnamate,    N-(β-carbomethoxy-β-cyanovinyl)-2-methylindoline, neopentyl    tetra(α-cyano-β,β-diphenylacrylate.-   24. Sterically hindered amines, for example carbonic acid    bis(1-undecyloxy-2,2,6,6-tetra-methyl-4-piperidyl)ester,    bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate,    bis(2,2,6,6-tetramethyl-4-piperidyl)succinate,    bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate,    bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate,    bis(1,2,2,6,6-pentamethyl-4-piperidyl)    n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of    1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and    succinic acid, linear or cyclic condensates of    N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and    4-tert-octylamino-2,6-dichloro-1,3,5-triazine,    tris(2,2,6,6-tetramethyl-4-piperidyl)nitrilotriacetate,    tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate,    1,1′-(1,2-ethanediyl)-bis(3,3,5,5-tetramethylpiperazinone),    4-benzoyl-2,2,6,6-tetramethylpiperidine,    4-stearyloxy-2,2,6,6-tetramethylpiperidine,    bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate,    3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione,    bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate,    bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate, linear or    cyclic condensates of    N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and    4-morpholino-2,6-dichloro-1,3,5-triazine, the condensate of    2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine    and 1,2-bis(3-aminopropylamino)ethane, the condensate of    2-chloro-4,6-di-(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazine    and 1,2-bis(3-aminopropylamino)ethane,    8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione,    3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5-dione,    3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)pyrrolidine-2,5-dione,    a mixture of 4-hexadecyloxy- and    4-stearyloxy-2,2,6,6-tetramethylpiperidine, a condensate of    N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and    4-cyclohexylamino-2,6-dichloro-1,3,5-triazine, a condensate of    1,2-bis(3-aminopropylamino)ethane and 2,4,6-trichloro-1,3,5-triazine    as well as 4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No.    [136504-96-6]); a conden-sate of 1,6-hexanediamine and    2,4,6-trichloro-1,3,5-triazine as well as N,N-dibutylamine and    4-butylamino-2,2,6,6-tetramethylpiperidine (CAS Reg. No.    [192268-64-7]);    N-(2,2,6,6-tetramethyl-4-piperidyl)-n-dodecylsuccinimide,    N-(1,2,2,6,6-pentamethyl-4-piperidyl)-n-dodecylsuccinimide,    2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxo-spiro[4,5]decane,    a reaction product of    7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro-[4,5]decane    and epichlorohydrin,    1,1-bis(1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyl)-2-(4-methoxyphenyl)ethene,    N,N′-bis-formyl-N,N′-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine,    a diester of 4-methoxymethylenemalonic acid with    1,2,2,6,6-pentamethyl-4-hydroxypiperidine,    poly[methylpropyl-3-oxy-4-(2,2,6,6-tetramethyl-4-piperidyl)]siloxane,    a reaction product of maleic acid anhydride-α-olefin copolymer with    2,2,6,6-tetramethyl-4-aminopiperidine or    1,2,2,6,6-pentamethyl-4-aminopiperidine,    2,4-bis[N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidine-4-yl)-N-butylamino]-6-(2-hydroxyethyl)amino-1,3,5-triazine,    1-(2-hydroxy-2-methylpropoxy)-4-octadecanoyloxy-2,2,6,6-tetramethylpiperidine,    5-(2-ethylhexanoyl)oxymethyl-3,3,5-trimethyl-2-morpholinone,    Sanduvor (Clariant; CAS Reg. No. 106917-31-1],    5-(2-ethylhexanoyl)oxymethyl-3,3,5-trimethyl-2-morpholinone, the    reaction product of    2,4-bis[(1-cyclohexyloxy-2,2,6,6-piperidine-4-yl)butylamino]-6-chloro-s-triazine    with N,N′-bis(3-aminopropyl)ethylenediamine),    1,3,5-tris(N-cyclohexyl-N-(2,2,6,6-tetramethylpiperazine-3-one-4-yl)amino)-s-triazine,    1,3,5-tris(N-cyclohexyl-N-(1,2,2,6,6-pentamethylpiperazine-3-one-4-yl)amino)-s-triazine.-   25. Oxamides, for example 4, 4′-dioctyloxyoxanilide,    2,2′-diethoxyoxanilide, 2,2′-dioctyloxy-5,5′-di-tert-butoxanilide,    2,2′-didodecyloxy-5,5′-di-tert-butoxanilide,    2-ethoxy-2′-ethyloxanilide, N,N′-bis(3-dimethylaminopropyl)oxamide,    2-ethoxy-5-tert-butyl-2′-ethoxanilide and its mixture with    2-ethoxy-2′-ethyl-5,4′-di-tert-butoxanilide, mixtures of o- and    p-methoxy-disubstituted ox-anilides and mixtures of o- and    p-ethoxydisubstituted oxanilides.-   26. 2-(2-Hydroxyphenyl)-1,3,5-triazines, for example 2,    4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine,    2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,    2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,    2,4-bis(2-hydroxy-4-propyloxyphenyl)-6-(2,4-dimethylphenyl)-1,3,5-triazine,    2-(2-hydroxy-4-octyloxyphenyl)-4,6-bis(4-methylphenyl)-1,3,5-triazine,    2-(2-hydroxy-4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,    2-(2-hydroxy-4-tridecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,    2-[2-hydroxy-4-(2-hydroxy-3-butyloxypropoxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine,    2-[2-hydroxy-4-(2-hydroxy-3-octyloxypropyloxy)phenyl]-4,6-bis(2,4-dimethyl)-1,3,5-triazine,    2-[4-(dodecyloxy/tridecyloxy-2-hydroxypropoxy)-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,    2-[2-hydroxy-4-(2-hydroxy-3-dodecyloxypropoxy)phenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,    2-(2-hydroxy-4-hexyloxy)phenyl-4,6-diphenyl-1,3,5-triazine,    2-(2-hydroxy-4-methoxyphenyl)-4,6-diphenyl-1,3,5-triazine,    2,4,6-tris[2-hydroxy-4-(3-butoxy-2-hydroxypropoxy)phenyl]-1,3,5-triazine,    2-(2-hydroxyphenyl)-4-(4-methoxyphenyl)-6-phenyl-1,3,5-triazine,    2-{2-hydroxy-4-[3-(2-ethylhexyl-1-oxy)-2-hydroxypropyloxy]phenyl}-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine,    2,4-bis(4-[2-ethylhexyloxy]-2-hydroxyphenyl)-6-(4-methoxyphenyl)-1,3,5-triazine.

When used in combination with resins, the electrolyte andnon-electrolytic, acidifying components of the inventedoxygen-scavenging composition, and any optional water-absorbent binderthat may be used, are e.g. used in particulate or powder form. Particlesizes of at least 290 μm or smaller are preferred to facilitatemelt-processing of oxygen-scavenger thermoplastic resin formulations.For use with thermoset resins for formation of coatings, particle sizessmaller than the thickness of the final coating are advantageouslyemployed. The oxygen-scavenger composition can be used directly inpowder or particulate form, or it can be processed, for example by meltcompounding or compaction-sintering, into pellets to facilitate furtherhandling and use. The mixture of the oxidizable metal component,electrolyte component, non-electrolytic, acidifying component andoptional water-absorbent binder can be added directly to a thermoplasticpolymer compounding or melt-fabrication operation, such as in theextrusion section thereof, after which the molten mixture can beadvanced directly to a film or sheet extrusion or coextrusion line toobtain monolayer or multilayer film or sheet in which the amount ofoxygen-scavenging composition is determined by the proportions in whichthe mixture and resin are combined in the resin feed section of theextrusion-fabrication line. Alternatively, the mixture of the oxidizablemetal component, electrolyte component, non-electrolytic, acidifyingcomponent and optional binder can be compounded into masterbatchconcentrate pellets, which can be further let down into packaging resinsfor further processing into extruded film or sheet, or injection moldedarticles such as tubs, bottles, cups, trays and the like.

The degree of mixing of oxidizable metal, electrolyte andnon-electrolytic acidifying components and, if used, optional bindercomponent, may affect oxygen absorption performance of theoxygen-scavenging composition with better mixing leading to betterperformance. Mixing effects may be most noticeable at low electrolyteplus non-electrolytic, acidifying components to oxidizable metalcomponent ratios and at very low and very high non-electrolytic,acidifying component to electrolyte component ratios. Below e.g. 10parts by weight of electrolyte plus non-electrolytic, acidifyingcomponents per 100 parts by weight of metal component, or when theweight ratio of either the electrolyte or non-electrolytic, acidifyingcomponent to the other is less than about 10:90, the oxygen-scavengercomponents are preferably mixed by aqueous slurry mixing followed byoven drying and grinding into fine particles. Below these ratios, mixingby techniques suitable at higher ratios, such as by high-intensitypowder mi-xing, as in a Henschel mixer or a Waring powder blender, or bylower intensity mixing techniques, as in a container on a roller ortumbler, may lead to variability in oxygen uptake, particularly when themixtures are incorporated into thermoplastic resins and used in meltprocessing operations.

Other factors that may affect oxygen absorption performance of theinvented oxygen-scavenging composition include surface area of articlesincorporating the compositions, with greater surface area normallyproviding better oxygen absorption performance. The amount of residualmoisture in the water-absorbant binder, if used, also can affectperformance with more moisture in the binder leading to better oxygenabsorption performance. However, there are practical limits on theamount of moisture that should be present in the binder because too muchcan cause premature activation of the oxygen-scavenger composition aswell as processing difficulties and poor aesthetics in fabricatedproducts. When incorporated into thermoplastic resins and used forfabrication of articles by melt processing techniques, the nature of theresin also can have a significant effect. Thus, when the inventedoxygen-scavenging composition is used with amorphous and/or oxygenpermeable polymers such as polyolefins or amorphous polyethyleneterephthalate, higher oxygen absorption is seen than when thecompositions are used with crystalline and/or oxygen barrier polymerssuch as crystalline polyethylene terephthalate and EVOH.

When used with thermoplastic resins, the oxygen-scavenging compositioncan be incurporated directly into the resin in amounts effective toprovide the desired level of oxygen-scavenging ability. When so-used,preferred oxygen scavenger levels will vary depending on the choice ofresin, configuration of the article to be fabricated from the resin andoxygen-scavenging capability needed in the article. Use of resins withlow inherent viscosity, e.g., low molecular weight resins, normallypermits higher loadings of scavenger composition without loss ofprocessability. Conversely, lesser amounts of oxygen-scavengercomposition may facilitate use of polymeric materials having higherviscosities. Preferably, at least 0.1 parts by weight ofoxygen-scavenging composition are used per 100 parts by of weight ofresin. Loading levels above 200 parts per 100 parts of resin generallydo not lead to gains in oxygen absorption and may interfere withprocessing and adversely affect other product properties. Morepreferably, loading levels of e.g. 0.2 to 150 parts, in particular 0.3to 50 parts or 5 to 50 parts, per 100 parts of resin are used to obtaingood scavenging performance while maintaining processibility. Loadinglevels of 0.3 to 20 parts per 100 parts of resin are particularlypreferred for fabrication of thin films and sheets.

Preferred oxygen-scavenger resin compositions for fabrication ofpackaging articles comprise at least one thermoplastic resin and e.g. 2to 50 parts or 5 to 50 parts by weight of oxygen-scavenging compositionper 100 parts by weight of resin, with the oxygen-scavenging compositioncomprising iron powder as component (I), NaCl, KCl or CaCl₂ as component(II) and Na₂H₂P₂O₇ or CaH₂P₂O₇ as component (III) optionally incombination with NaH₂PO₄, KH₂PO₄ or Ca(H₂PO₄)₂ as component (IIIa). Morepreferably, e.g. 30 to 130 parts by weight of component (II) pluscomponent (III) (=component (III) plus optionally component (IIIa)) per10 parts by weight of iron are present in the scavenging composition andthe weight ratio of component (II) to component (III) is e.g. 10:90 to90:10. Up to e.g. 50 parts by weight of water-absorbant binder per 100parts by weight of resin and oxygen-scavenger also can be included.Especially preferred compositions of this type comprise polypropylene,high, low or linear low density polyethylene or polyethyleneterephthalate as the resin, e.g. 5 to 30 parts by weight ofoxygen-scavenger per 100 parts by weight of resin. Preferred is e.g. 5to 100 parts by weight of component (II) and 5 to 70 parts by weight ofcomponent (III) per 10 parts by weight of iron and e.g. 0 to 50 parts byweight of binder per 100 parts by weight of components (I), (II), (III)and (IV).

While the oxygen-scavenging composition and resin can be used in anon-concentrated form for direct fabrication of scavenging sheets orfilms (i.e., without further resin dilution), it also is beneficial touse the oxygen-scavenging composition and resin in the form of aconcentrate or masterbatch. When so-used, the ability to produce aconcentrate with low materials cost weighs in favor of relatively highloadings of scavenger that will still permit successful meltcompounding, such as by extrusion pelletization. Thus, concentratecompositions according to the invention preferably contain at least e.g.10 parts by weight of oxygen-scavenging composition per 100 parts byweight of resin and more preferably 30 to 150 parts per 100 parts ofresin. Suitable resins for such oxygen-scavenging concentratecompositions include any of the thermoplastic polymer resins describedherein. Low melt viscosity resins facilitate use of high scavengerloadings and typically are used in small enough amounts in meltfabrication of finished articles that the typically lower molecularweight of the concentrate resin does not adversely affect final productproperties. Preferred carrier resins are polypropylene, high density,low density and linear low density polyethylenes and polyethyleneterephthalate. Preferred among those are polypropylenes having melt flowrates of e.g. 1 to 40 g/10 min, polyethylenes having melt indices ofe.g. 1 to 20 g/10 min and polyethylene terephthalates having inherentviscosities of e.g. 0.6 to e.g. 1 in phenol/trichloroethane.

It is also contemplated to utilize various components of theoxygen-scavenging composition or combinations of such components to formtwo or more concentrates that can be combined with a thermoplastic resinand fabricated into an oxygen-scavenging product. An advantage of usingtwo or more concentrates is that the electrolyte and non-electrolytic,acidifying components can be isolated from the oxidizable metal untilpreparation of finished articles, the-reby preserving full oressentially full oxygen-scavenging capability until actual use andpermitting lower scavenger loadings than would otherwise be required. Inaddition, separate concentrates permit more facile preparation ofdiffering concentrations of the electrolyte and non-electolytic,acidifying components and/or water absorbant binder with the oxidizablemetal and also enable fabricators to conveniently formulate a wide rangeof melt-processible resin compositions in which oxygen-scavengingability can be tailored to specific end use requirements. Preferredcomponents or combinations of components for use in separateconcentrates are (a) acidifying component; (b) combinations ofoxidizable metal component with water absorbing binder component; and(c) combinations of electrolyte and non-electrolytic acidifyingcomponents.

A particularly preferred component concentrate is a compositioncomprising Na₂H₂P₂O₇ or CaH₂P₂O₇ and a thermoplastic resin. Such aconcentrate can be added in desired amounts in melt fabricationoperations utilizing thermoplastic resin that already contains, or towhich will be added, other scavenging components, such as a oxidizablemetal or combination thereof with an electrolyte, to provide enhancedoxygen-scavenging capability. Especially preferred are concentratescontaining e.g. 10 to e.g. 150 parts by weight of component (III) per100 parts by weight of resin, with polypropylene, polyethylenes andpolyethylene tere-phthalate being most preferred resins.

Thus, a further embodiment of the present invention is a masterbatchcomprising

(A) a polymeric resin, and

(B) 30 to 150% by weight, based on the polymeric resin, of theoxygen-scavenging composition as described herein.

Polymeric resins that can be used for incorporating theoxygen-scavenging composition into internal coatings of cans via spraycoating and the like are typically thermoset resins such as epoxy,oleoresin, unsaturated polyester resins or phenolic based materials.

Another embodiment of the present invention is an article containing acomposition as described above. The article may be a film, a laminate(e.g. a coextruded multilayer film), a sheet or a rigid or flexiblepackage (e.g. a food packaging).

In more detail, these articles of manufacture comprise at least onemelt-fabricated layer containing the oxygen-scavenging composition asdescribed above. Because of the improved oxidation efficiency affordedby the invented oxygen-scavenging composition, the scavenger-containinglayer can contain relatively low levels of the scavenger. The articlesof the present invention are well suited for use in flexible or rigidpackaging structures. In the case of rigid sheet packaging according tothe invention, the thickness of the oxygen-scavenging layer ispreferably not greater than e.g. 2500 μm, and is most preferably in therange of 50 to 1300 μm. In the case of flexible film packaging accordingto the invention, the thickness of the oxygen scavenger layer ispreferably not greater than e.g. 250 μm and, most preferably, 10 to 200μm. Packaging structures according to the invention can be in the formof films or sheets, both rigid and flexible, as well as container orvessel walls and liners as in trays, cups, bowls, bottles, bags,pouches, boxes, films, cap liners, can coatings and other packagingconstructions. Both monolayer and multilayer structures arecontemplated.

The oxygen-scavenging composition and resin of the present inventionafford active-barrier properties in articles fabricated therefrom andcan be melt processed by any suitable fabrication technique intopackaging walls and articles having excellent oxygen barrier propertiesthat can avoid to include layers of costly gas barrier films such asthose based on EVOH, PVDC, metallized polyolefin or polyester, aluminumfoil, silica coated polyolefin and polyester, etc. The oxygen-scavengerarticles of the present invention also provide the additional benefit ofimproved recyclability. Scrap or reclaim from the oxygen-scavengingresin can be easily recycled back into plastic products without adverseeffects. In contrast, recycle of EVOH or PVDC gas barrier films maycause deterioration in product quality due to polymer phase separationand gelation occurring between the gas barrier resin and other resinsmaking up the product. Nevertheless, it also is contemplated to providearticles, particularly for packaging applications, with both active andpassive oxygen barrier properties through use of one or more passive gasbarrier layers in articles containing one or more active barrier layersaccording to the invention. Thus, for some applications, such aspackaging for food for institutional use and others calling for longshelf-life, an oxygen-scavenging layer according to the presentinvention can be used in conjunction with a passive gas barrier layer orfilm such as those based on EVOH, PVDC, metallized polyolefins oraluminum foil.

The present invention is also preferably directed to a packaging wallcontaining at least one layer comprising the oxygen-scavengingcomposition and resin described above. It should be understood that anypackaging article or structure intended to completely enclose a productwill be deemed to have a “packaging wall,” as that term is used herein,if the packaging article comprises a wall, or portion thereof, that is,or is intended to be, interposed between a packaged product and theatmosphere outside of the package and such wall or portion thereofcomprises at least one layer incorporating the oxygen-scavengingcomposition of the present invention. Thus, bowls, bags, liners, trays,cups, cartons, pouches, boxes, bottles and other vessels or containerswhich are intended to be sealed after being filled with a given productare covered by the term “packaging wall” if the oxygen-scavengingcomposition of the invention is present in any wall of such vessel (orportion of such wall) which is inter-posed between the packaged productand the outside environment when the vessel is closed or sealed. Oneexample is where the oxygen-scavenging composition of the invention isfabricated into, or between, one or more continuous thermoplastic layersenclosing or substantially enclosing a product. Another example of apackaging wall according to the invention is a monolayer or multilayerfilm containing the present oxygen-scavenging composition used as a capliner in a beverage bottle (i.e., for beer, wine, fruit juices, etc.) oras a wrapping material.

An attractive active-barrier layer is generally understood as one inwhich the kinetics of the oxidation reaction are fast enough, and thelayer is thick enough, that most of the oxygen permeating into the layerreacts without allowing a substantial amount of the oxygen to transmitthrough the layer. Moreover, it is important that this “steady state”condition exist for a pe-riod of time appropriate to end userequirements before the scavenger layer is spent. The present inventionaffords this steady state, plus excellent scavenger longevity, ineconomically attractive layer thicknesses, for example, less than e.g.2500 μm in the case of sheets for rigid packaging, and less than e.g.250 μm in the case of flexible films. For rigid sheet packagingaccording to the present invention, an attractive scavenger layer can beprovided in the range of 250 to 750 μm, while for flexible filmpackaging, layer thicknesses of 20 to 200 μm are attractive. Such layerscan function efficiently with as little as e.g. 2 to 10 weight % ofoxygen-scavenger composition based on weight of the scavenger layer.

In fabrication of packaging structures according to the invention, it isimportant to note that the oxygen-scavenging resin composition of theinvention is substantially inactive with res-pect to chemical reactionwith oxygen so long as the water activity of the composition is notsufficient. In contrast, the composition becomes active for scavengingoxygen when the water activity reaches a particularly level. Wateractivity is such that, prior to use, the invented packaging articles canremain substantially inactive in relatively dry environments withoutspecial steps to maintain low moisture levels. However, once thepackaging is placed into use, most products will have sufficientmoisture to activate the scavenger composition incor-porated in thewalls of the packaging article.

To prepare a packaging wall according to the invention, anoxygen-scavenging resin formula-tion is used or the oxygen-scavengingcomposition, or its components or concentrates thereof, is compoundedinto or otherwise combined with a suitable packaging resin whereupon theresulting resin formulation is fabricated into sheets, films or othershaped structures. Extrusion, coextrusion, blow molding, injectionmolding and any other sheet, film or general polymeric melt-fabricationtechnique can be used. Sheets and films obtained from theoxygen-scavenger composition can be further processed, e.g. by coatingor lamination, to form multilayered sheets or films, and then shaped,such as by thermoforming or other forming operations, into desiredpackaging walls in which at least one layer contains the oxygenscavenger. Such packaging walls can be subjected to further processingor shaping, if desired or necessary, to obtain a variety ofactive-barrier end-use packaging articles. The present invention reducesthe cost of such barrier articles in comparison to conventional articleswhich afford barrier properties using passive barrier films.

As a preferred article of manufacture, the invention provides apackaging article comprising a wall, or combination of interconnectedwalls, in which the wall or combination of walls defines an enclosableproduct-receiving space, and wherein the wall or combination of wallscomprises at least one wall section comprising an oxygen-scavenginglayer comprising (i) an ethoxylated additive (ii) an oxidizable metalpreferably comprising at least one member selected from the groupconsisting of Al, Mg, Zn, Cu, Fe, Sn, Co or Mn, and most preferably 0.1to 100 parts of iron per 100 parts by weight of the resin; (iii) anelectrolyte component and a solid, non-electrolytic, acidifyingcomponent which in the presence of water has a pH of less than 7, withe.g. 5 to about 150 parts by weight of such components per 10 parts byweight of iron preferably being present and the weight ratio of thenon-electrolytic, acidifying component to electrolyte componentpreferably being about 5/95 to about 95/5; an polymeric resin differentfrom the componet (i) and, optionally, a water-absorbent binder.

A particularly attractive packaging construction according to theinvention is a packaging wall comprising a plurality of thermoplasticlayers adhered to one another in bonded laminar con-tact wherein atleast one oxygen-scavenging layer is adhered to one or more other layerswhich may or may not include an oxygen-scavenging composition. It isparticularly preferred, although not required, that the thermoplasticresin constituting the major component of each of the layers of thepackaging wall be the same, so as to achieve a “pseudo-monolayer”. Sucha construction is easily recyclable.

An example of a packaging article using the packaging wall describedabove is a two-layer or three-layer dual ovenable tray made ofcrystalline polyethylene terephthalate (“C-PET”) suitable for packagingpre-cooked single-serving meals. In a three-layer construction, anoxygen-scavenging layer of 250 to 500 μm thickness is sandwiched betweentwo non-scavenging C-PET layers of 70 to 250 μm thickness. The resultingtray is considered a “pseudo-monolayer” because, for practical purposesof recycling, the tray contains a single thermoplastic resin, i.e.,C-PET. Scrap from this pseudo-monolayer tray can be easily recycledbecause the scavenger in the center layer does not detract fromrecyclability. In the C-PET tray, the outer, non-scavenging layerprovides additional protection against oxygen transmission by slowingdown the oxygen so that it reaches the center layer at a sufficientlyslow rate that most of the ingressing oxygen can be absorbed by thecenter layer without permeating through it. The optional innernon-scavenging layer acts as an additional barrier to oxygen, but at thesame time is permeable enough that oxygen inside the tray may pass intothe cen-tral scavenging layer. It is not necessary to use a three layerconstruction. For example, in the above construction, the inner C-PETlayer can be eliminated. A tray formed from a single oxygen scavenginglayer is also an attractive construction.

The pseudo-monolayer concept can be used with a wide range of polymericpackaging ma-terials to achieve the same recycling benefit observed inthe case of the pseudo-monolayer C-PET tray. For example, a packagefabricated from polypropylene or polyethylene can be prepared from amultilayer packaging wall (e.g., film) containing the oxygen-scavengingcomposition of the present invention. In a two-layer construction thescavenger layer can be an interior layer with a non-scavenging layer ofpolymer on the outside to provide additional barrier properties. Asandwich construction is also possible in which a layer ofscavenger-containing resin, such as polyethylene, is sandwiched betweentwo layers of non-scavenging polyethylene. Alternatively, polypropylene,polystyrene or another suitable resin can be used for all of the layers.

Various modes of recycle may be used in the fabrication of packagingsheets and films according to the invention. For example, in the case ofmanufacturing a multilayer sheet or film having a scavenging andnon-scavenging layer, reclaim scrap from the entire multilayer sheet canbe recycled back into the oxygen scavenging layer of the sheet or film.It is also possible to recycle the multilayer sheet back into all of thelayers of the sheet.

Packaging walls and packaging articles according to the presentinvention may contain one or more layers which are foamed. Any suitablepolymeric foaming technique, such as bead foaming or extrusion foaming,can be utilized. For example, a packaging article can be obtained inwhich a foamed resinous layer comprising, for example, foamedpolystyrene, foamed polyester, foamed polypropylene, foamed polyethyleneor mixtures thereof, can be adhered to a solid resinous layer containingthe oxygen-scavenging composition of the present invention.Alternatively, the foamed layer may contain the oxygen-scavengingcomposition, or both the foamed and the non-foamed layer can contain thescavenging composition. Thicknesses of such foamed layers normally aredictated more by mechanical property requirements, e.g. rigidity andimpact strenth, of the foam layer than by oxygen-scavengingrequirements.

Packaging constructions such as those described above can benefit fromthe ability to eliminate costly passive barrier films. Nevertheless, ifextremely long shelf life or added oxygen protection is required ordesired, a packaging wall according to the invention can be fabricatedto include one or more layers of EVOH, nylon or PVDC, or even ofmetallized polyolefin, metallized polyester, or aluminum foil. Anothertype of passive layer which may be enhanced by an oxygen-scavengingresin layer according to the present invention is silica-coatedpolyester or silica-coated polyolefin. In cases where a multilayerpackaging wall according to the invention contains layers of differentpolymeric compositions, it may be preferable to use adhesive layers suchas those based on ethylene-vinyl acetate copolymer or maleatedpolyethylene or polypropylene, and if desired, the oxygen-scavenger ofthe present invention can be incorporated in such adhesive layers. It isalso possible to prepare the oxygen-scavenging composition of thepresent invention using a gas barrier resin such as EVOH, nylon or PVDCpolymer in order to obtain a film having both active and passive barrierproperties.

While the focus of one embodiment of the invention is upon theincorporation of the oxygen-scavenging composition directly into thewall of a container, the oxygen-scavenging compo-sition also can be usedin packets, as a separate inclusion within a packaging article where theintent is only to absorb headspace oxygen.

A primary application for the oxygen-scavenging resin, packaging walls,and packaging ar-ticles of the invention is in the packaging ofperishable foods. For example, packaging articles utilizing theinvention can be used to package milk, yogurt, ice cream, cheeses; stewsand soups; meat products such as hot dogs, cold cuts, chicken, beefjerky; single-serving pre-cooked meals and side dishes; homemade pastaand spaghetti sauce; condiments such as barbecue sauce, ketchup,mustard, and mayonnaise; beverages such as fruit juice, wine, and beer;dried fruits and vegetables; breakfast cereals; baked goods such asbread, crackers, pastries, cookies, and muffins; snack foods such ascandy, potato chips, cheese-filled snacks; peanut butter or peanutbutter and jelly combinations, jams, and jellies; dried or freshseasonings; and pet and animal foods; etc. The foregoing is not intendedto be limiting with respect to the possible applications of theinvention. Generally speaking, the invention can be used to enhance thebarrier properties in packaging materials intended for any type ofproduct which may degrade in the presence of oxygen.

Still other applications for the oxygen-scavenging compositions of thisinvention include the internal coating of metal cans, especially foroxygen-sensitive food items such as tomato-based materials, baby foodand the like. Typically the oxygen-scavenging composition can becombined with polymeric resins such as thermosets of epoxy, oleoresin,unsaturated polyester resins or phenolic based materials and thematerial applied to the metal can by methods such as roller coating orspray coating.

Thus, a further embodiment of the invention is the use of a mixturecomprising components (I) to (IV) as defined above as oxygen-scavengerin food packaging.

An over view of the various applications which are possible for thepresent oxygen-scavenging composition is described for example in U.S.Pat. No. 5,744,056, U.S. Pat. No. 5,885,481, U.S. Pat. No. 6,369,148 andU.S. Pat. No. 6,586,514, which are incorporated by reference herein.

The examples below illustrate the invention in greater detail. Allpercentages and parts are by weight, unless stated otherwise.

Comparative Sample 1:

NaCl, Na₂H₂P₂O₇ and NaH₂PO₄ are mixed with low density polyethylene(Riblene GP20®) so that the ratios NaCl/Na₂H₂P₂O₇/NaH₂PO₄ are1/0.92/0.08 by weight, and the final concen-tration of NaCl is 3.5% byweight. Fe particles are added at a concentration (by weight) of 7.0%using common electrolytic iron powder, minus 325 mesh (<44 nm). Thecompositions are prepared with an OMC pilot double screw extruder (modelEBV 19/25, with a 19 mm screw diameter and 1:25 ratio), and 50micron-thick films are prepared using a Formac Blow Extruder (modelLab25, with a 22 mm screw diameter and 1:25 ratio).

Comparative Sample 2:

NaCl and Na₂H₂P₂O₇ are mixed with polypropylene (RD208CF®) so that theratios NaCl/Na₂H₂P₂O₇ are 1/0.50 by weight, and the final concentrationof NaCl is 7.0% by weight. Fe particles are added at a concentration (byweight) of 7.0% using common electrolytic iron powder, minus 325 mesh(<44 nm). The compositions are prepared with an OMC pilot double screwextruder (model EBV 19/25, with a 19 mm screw diameter and 1:25 ratio),and 100 micron-thick films are prepared using Collin Cast FlatdieExtruder model 30×25 L/D (30 mm screw diameter, 1:25 diameter/lengthratio).

Inventive Sample 1:

NaCl, Na₂H₂P₂O₇, NaH₂PO₄ and a fatty alkyl polyethylene glycol ether(Lutensol AT25®) are mixed with low density polyethylene (Riblene GP20®)so that the ratios NaCl/Na₂H₂P₂O₇/NaH₂PO₄/fatty alkyl polyethyleneglycol ether are 1/0.92/0.08/0.57 by weight, and the final concentrationof NaCl is 3.5% by weight. Fe particles are added at a differentconcentration (by weight) of 7.0% using common electrolytic iron powder,minus 325 mesh (<44 nm). Samples are prepared as described forComparative Sample 1.

Inventive Sample 2:

NaCl, Na₂H₂P₂O₇, NaH₂PO₄ and a fatty alkyl polyethylene glycol ether(Lutensol AO30®) are mixed with low density polyethylene (Riblene GP20®)so that the ratios NaCl/Na₂H₂P₂O₇/NaH₂PO₄/fatty alkyl polyethyleneglycol ether are 1/0.92/0.08/0.57 by weight, and the final concentrationof NaCl is 3.5% by weight. Fe particles are added at a differentconcentration (by weight) of 7.0% using common electrolytic iron powder,minus 325 mesh (<44 μm). Samples are prepared as described forComparative Sample 1.

Inventive Sample 3:

NaCl, Na₂H₂P₂O₇, NaH₂PO₄ and a polyethylene glycol (Pluriol E1500®) aremixed with low density polyethylene (Riblene GP20®) so that the ratiosNaCl/Na₂H₂P₂O₇/NaH₂PO₄/polyethylene glycol are 1/0.92/0.08/0.57 byweight, and the final concentration of NaCl is 3.5% by weight. Feparticles are added at a different concentration (by weight) of 7.0%using common electrolytic iron powder, minus 325 mesh (<44 μm). Samplesare prepared as described for Comparative Sample 1.

Inventive Sample 4:

NaCl, Na₂H₂P₂O₇, NaH₂PO₄ and a polyethylene glycol (Pluriol E1500®) aremixed with low density polyethylene (Riblene GP20®) so that the ratiosNaCl/Na₂H₂P₂O₇/NaH₂PO₄/polyethylene glycol are 1/0.92/0.08/0.41 byweight, and the final concentration of NaCl is 2.45% by weight. Feparticles are added at a different concentration (by weight) of 4.9%using common electrolytic iron powder, minus 325 mesh (<44 μm). Samplesare prepared as described for Comparative Sample 1.

Inventive Sample 5:

NaCl, Na₂H₂P₂O₇, NaH₂PO₄ and a polyethylene glycol (Pluriol E1500®) aremixed with low density polyethylene (Riblene GP20®) so that the ratiosNaCl/Na₂H₂P₂O₇/NaH₂PO₄/polyethylene glycol are 1/0.92/0.08/0.31 byweight, and the final concentration of NaCl is 3.5% by weight. Feparticles are added at a different concentration (by weight) of 7.0%using common electrolytic iron powder, minus 325 mesh (<44 μm). Samplesare prepared as described for Comparative Sample 1.

Inventive Sample 6:

NaCl, Na₂H₂P₂O₇, NaH₂PO₄ and a polypropylene glycol/polyethylene glycolblock copolymer (Pluronic PE6800®) are mixed with low densitypolyethylene (Riblene GP20®) so that the ratiosNaCl/Na₂H₂P₂O₇/NaH₂PO₄/polypropylene glycol/polyethylene glycol blockcopolymer are 1/0.92/0.08/0.57 by weight, and the final concentration ofNaCl is 3.5% by weight. Fe particles are added at a differentconcentration (by weight) of 7.0% using common electrolytic iron powder,minus 325 mesh (<44 μm). Samples are prepared as described forComparative Sample 1.

Inventive Sample 7:

NaCl, Na₂H₂P₂O₇, NaH₂PO₄ and a polyethylene block poly(ethylene glycol)(CAS 251553-55-6 from Aldrich) are mixed with low density polyethylene(Riblene GP20®) so that the ratios NaCl/Na₂H₂P₂O₇/NaH₂PO₄/polyethyleneblock poly(ethylene glycol) are 1/0.92/0.08/0.57 by weight, and thefinal concentration of NaCl is 3.5% by weight. Fe particles are added ata different concentration (by weight) of 7.0% using common electrolyticiron powder, minus 325 mesh (<44 μm). Samples are prepared as describedfor Comparative Sample 1.

Several aliquots of film for each sample are then exposed to air (20.7%O₂) in 500 ml sealed flasks provided with a septum that allowed portionsof the inside atmosphere to be drawn for analysis at several intervalsusing a syringe, in the presence of 15 ml water contained in a vialinside the flasks. Oxygen concentration measures are carried out using aMocon Pac Check 450 head space analyzer over 28 days. The actual ironconcentrations in the samples tested are finally measured by ICP-OES(Inductively Coupled Plasma-Optical Emission Spectrometer, Perkin ElmerOptima Series 4200DV). The results in terms of ml O₂/gr of iron aregiven in Table 1.

TABLE 1 ml O₂/gr Iron After 28 Days* Comparative Sample 1 32 InventiveSample 1 106 Inventive Sample 2 76 Inventive Sample 3 92 InventiveSample 4 88 Inventive Sample 5 101 Inventive Sample 6 62 InventiveSample 7 69 *Averaged oxygen scavenger activity (ml O₂/gr Iron) for sixdifferent LDPE film measured after 28 days.

Table 1 clearly shows that oxygen scavenger activity of InventiveSamples from 1 to 7 is greater than the oxygen scavenger activity ofComparative Sample 1

Inventive Sample 8:

NaCl, Na₂H₂P₂O₇ and a polyethylene glycol (Pluriol E1500®) are mixedwith polypropylene (RD208CF®) so that the ratiosNaCl/Na₂H₂P₂O₇/polyethylene glycol are 1/0.5/0.28 by weight, and thefinal concentration of NaCl is 7.0% by weight. Fe particles are added ata concentration (by weight) of 7.0% using common electrolytic ironpowder, minus 325 mesh (<44 μm). Samples are prepared as described forComparative Sample 2.

Inventive Sample 9:

NaCl, Na₂H₂P₂O₇ and a polyethylene glycol (Pluriol E1500®) are mixedwith polypropylene (RD208CF®) so that the ratiosNaCl/Na₂H₂P₂O₇/polyethylene glycol are 1/0.5/0.14 by weight, and thefinal concentration of NaCl is 7.0% by weight. Fe particles are added ata concentration (by weight) of 7.0% using common electrolytic ironpowder, minus 325 mesh (<44 μm). Samples are prepared as described forComparative Sample 2.

Inventive Sample 10:

NaCl, Na₂H₂P₂O₇ and a polyethylene glycol (Pluriol E1500®) are mixedwith polypropylene (RD208CF®) so that the ratiosNaCl/Na₂H₂P₂O₇/polyethylene glycol are 1/0.5/0.07 by weight, and thefinal concentration of NaCl is 7.0% by weight. Fe particles are added ata concentration (by weight) of 7.0% using common electrolytic ironpowder, minus 325 mesh (<44 μm). Samples are prepared as described forComparative Sample 2.

Several aliquots of film for each sample are exposed to air (20.7% O₂)in 500 ml sealed flasks provided with a septum that allowed portions ofthe inside atmosphere to be drawn for analysis at several intervalsusing a syringe, in the presence of 15 ml water contained in a vialinside the flasks. Oxygen concentration measures are carried out at roomtemperature using a Mocon Pac Check 450 head space analyzer over 28days. The actual iron concentrations in the samples tested are finallymeasured by ICP-OES (Inductively Coupled Plasma—Optical EmissionSpectrometer, Perkin Elmer Optima Series 4200DV). The results in termsof ml O₂/gr of iron are given in Table 2 as average of five differentmeasurements on each film sample.

TABLE 2 ml O₂/gr Iron After 28 Days* Comparative Sample 2 39 InventiveSample 8 120 Inventive Sample 9 115 Inventive Sample 10 89 *Averagedoxygen scavenger activity (ml O₂/gr Iron) for four different PP filmmeasured after 28 days.

Table 2 clearly shows that oxygen scavenger activity of InventiveSamples from 8 to 10 is greater than the oxygen scavenger activity ofComparative Sample 2.

The amount of oxygen adsorbed by the test samples is determined from thechange in the oxygen concentration in the head space of a sealed glasscontainer. The test container has a headspace volume of about 500 ml andcontains atmospheric air so that about 100 ml of oxygen are availablefor reaction with the iron particles. In all the examples oxygenscavenger component percentages are in weight percents based on totalweight of the film composition.

Detailed Description of Oxygen Uptake Method:

Film thickness is measured and 4.00 grams of film are weighted. Theextruded film is folded and placed in a clean 500 ml sealed glasscontainer. A vial containing 15 ml of deionized water is added toproduce 100% relative humidity inside the glass container. The oxygencontent in the ambient air on day 0 (i.e. equal to the initial oxygencontent in the sealed glass container) is tested and recorded using aMocon Oxygen Analyzer. The glass containers with test films and watervials are stored at 22° C. (generally, room temperature) for 28 days.

The oxygen content in the sealed glass containers using a Mocon OxygenAnalyzer on day 28 are tested and recorded.

Based on the measured oxygen concentration that is left in the sealedglass container the volume of oxygen absorbed per gram of Scavenger hasbeen calculated using the formula:Oxygen absorbed (ml/g)={(% O₂)_(i)−(%O₂)_(f)}*0.01*V_(j)/(W_(F)*W_(S)/W_(B))where:(% O₂)_(i) Initial oxygen concentration in the sealed glass container(%)(% O₂)_(f) Oxygen concentration in the sealed glass container at day oftest (%)0.01: Conversion factorV_(j): Free air volume of the sealed glass container (ml) (total volumeof the sealed glass container less space occupied by vial and film,typically 440 ml)W_(F): Weight of film placed into the glass container (typically 4.0 g)W_(S): Weight of Oxygen Scavenger used to make blend (g)W_(B): Total weight of blend (g)

The invention claimed is:
 1. An oxygen-scavenging composition comprising(I) an oxidizable metal component, (II) an electrolyte componentselected from the group consisting of NaCl, KCl and CaCl₂, (III) analkali metal acid pyrophosphate or an alkaline earth metal acidpyrophosphate, and (IV) at least one non-ionic surfactant componentselected from the group consisting of alkyl polyethylene glycol ethersof formula (1)RO(CH₂CH₂O)_(x)H  (1) wherein either R is a linear saturated C₁₆-C₁₈fatty alcohol residue and x is a number of 11 to 80, or R is a C₁₃-C₁₅saturated predominantly unbranched oxo alcohol residue and x is a numberof 3 to
 30. 2. The oxygen-scavenging composition according to claim 1wherein R is a linear saturated C₁₆-C₁₈ fatty alcohol residue and x is anumber of 11 to
 80. 3. The oxygen-scavenging composition according toclaim 1 wherein R is a C₁₃-C₁₅ saturated predominantly unbranched oxoalcohol residue and x is a number of 3 to
 30. 4. The oxygen-scavengingcomposition according to claim 1 wherein the oxidizable metal is iron.5. The oxygen-scavenging composition according to claim 1 comprising (I)iron, (II) NaCl, (III) Na₂H₂P₂O₇ and (IV) at least one non-ionicsurfactant selected from the group consisting of alkyl polyethyleneglycol ethers of formula (1); and optionally further comprising ascomponent (IIIa) NaH₂PO₄.
 6. The oxygen-scavenging composition accordingto claim 1 further comprising (V) a polyolefin resin.
 7. Theoxygen-scavenging composition according to claim 1 further comprising atleast one additive selected from the group consisting of (C-1)water-absorbent binders, (C-2) UV absorbers, (C-3) antioxidants and(C-4) further light stabilizers.
 8. An article comprising thecomposition of claim
 1. 9. The article according to claim 8, which is afilm, a sheet or a laminate.
 10. The article according to claim 9 whichis a coextruded multilayer film.
 11. The article according to claim 8which is a food packaging.
 12. The oxygen-scavenging compositionaccording to claim 1 comprising (I) iron, (II) NaCl, KCl or CaCl₂, (III)Na₂H₂P₂O₇, (IIIa) NaH₂PO₄ and (IV) at least one non-ionic surfactantselected from the group consisting of alkyl polyethylene glycol ethersof formula (1).
 13. The oxygen-scavenging composition according to claim1 comprising (I) iron, (II) NaCl, (III) Na₂H₂P₂O₇, (IIIa) NaH₂PO₄ and(IV) at least one non-ionic surfactant selected from the groupconsisting of alkyl polyethylene glycol ethers of formula (1).
 14. Theoxygen-scavenging composition according to claim 1 comprising (I) iron,(II) NaCl, KCl or CaCl₂, (III) Na₂H₂P₂O₇, (IIIa) Na₂H₂PO₄, (IV) at leastone non-ionic surfactant selected from the group consisting of alkylpolyethylene glycol ethers of formula (1), and (V) a polyolefin resin.15. The oxygen-scavenging composition according to claim 1 comprising(I) iron, (II) NaCl, (III) Na₂H₂P₂O₇, (IIIa) NaH₂PO₄, (IV) at least onenon-ionic surfactant selected from the group consisting of alkylpolyethylene glycol ethers of formula (1), and (V) a polyolefin resin.16. The oxygen-scavenging composition according to claim 1 comprising(I) iron, (II) NaCl, KCl or CaCl₂, (III) Na₂H₂P₂O₇, (IIIa) NaH₂PO₄, (IV)at least one non-ionic surfactant selected from the group consisting ofalkyl polyethylene glycol ethers of formula (1), and (V) polyethylene orpolypropylene.
 17. The oxygen-scavenging composition according to claim1 comprising (I) iron, (II) NaCl, (III) Na₂H₂P₂O₇, (IIIa) NaH₂PO₄, (IV)at least one non-ionic surfactant selected from the group consisting ofalkyl polyethylene glycol ethers of formula (1), and (V) polyethylene orpolypropylene.
 18. The oxygen-scavenging composition of claim 1, whereinthe composition does not comprise an amine antioxidant.
 19. Theoxygen-scavenging composition of claim 1, consisting essentially of: (I)at least one oxidizable metal component, (II) at least one electrolytecomponent selected from the group consisting of NaCl, KCl and CaCl₂,(III) at least one alkali metal acid pyrophosphate and/or alkaline earthmetal acid pyrophosphate, and (IV) at least one non-ionic surfactantcomponent selected from the group consisting of alkyl polyethyleneglycol ethers of formula (1).
 20. The oxygen-scavenging composition ofclaim 1, consisting of: (I) at least one oxidizable metal component,(II) at least one electrolyte component selected from the groupconsisting of NaCl, KCl and CaCl₂, (III) at least one alkali metal acidpyrophosphate and/or alkaline earth metal acid pyrophosphate, and (IV)at least one non-ionic surfactant component selected from the groupconsisting of alkyl polyethylene glycol ethers of formula (1).
 21. Theoxygen-scavenging composition of claim 1, wherein an oxygen scavengingability of the composition is greater than an oxygen scavenging abilityof an otherwise-identical composition without the non-ionic surfactant.22. A method of improving an oxygen-scavenging ability of a composition,the method comprising: including a non-ionic surfactant in a compositionin need thereof, thereby obtaining the composition of claim 1, whereinthe non-ionic surfactant is at least one selected from the groupconsisting of alkyl polyethylene glycol ethers of formula (1).